Which of the following compound possesses Lewis acid character?
(1) `BF_(3)` (2) `SiF_(4)` (3) `PF_(5)`
Select the correct answer using the codes given below

Options

A. 1 alone
B. 1,2&3
C. 2 & 3
D. 1&3

Answer

To determine which of the given compounds possesses Lewis acid character, we need to analyze each compound based on the definition of Lewis acids. A Lewis acid is a substance that can accept an electron pair.

### Step-by-Step Solution:

1. **Identify the Compounds**:
We have three compounds to analyze:
- (1) BF3 (Boron Trifluoride)
- (2) SiF4 (Silicon Tetrafluoride)
- (3) PF5 (Phosphorus Pentafluoride)

2. **Analyze BF3**:
- **Boron (B)** has an atomic number of 5 and an electronic configuration of 1s² 2s² 2p¹.
- In BF3, boron can undergo excitation where one of its 2s electrons jumps to the 2p orbital, resulting in an electron configuration of 1s² 2s¹ 2p².
- This leaves one p orbital vacant, allowing BF3 to accept an electron pair from a Lewis base.
- **Conclusion**: BF3 possesses Lewis acid character.

3. **Analyze SiF4**:
- **Silicon (Si)** has an atomic number of 14 with an electronic configuration of 1s² 2s² 2p⁶ 3s² 3p².
- When Si forms SiF4, one 3s electron can be excited to the 3p orbital, leading to an electron configuration of 1s² 2s² 2p⁶ 3s¹ 3p³.
- The presence of vacant d orbitals allows SiF4 to accept electron pairs.
- **Conclusion**: SiF4 possesses Lewis acid character.

4. **Analyze PF5**:
- **Phosphorus (P)** has an atomic number of 15 with an electronic configuration of 1s² 2s² 2p⁶ 3s² 3p³.
- In PF5, one of the 3s electrons can be promoted to the 3d orbital, resulting in the configuration of 1s² 2s² 2p⁶ 3s¹ 3p³ 3d¹.
- The presence of vacant d orbitals allows PF5 to accept electron pairs.
- **Conclusion**: PF5 possesses Lewis acid character.

5. **Final Conclusion**:
All three compounds (BF3, SiF4, and PF5) exhibit Lewis acid character because they can accept electron pairs. Therefore, the correct answer is option (2) - 1, 2, and 3.

### Summary of the Answer:
The compounds that possess Lewis acid character are:
- (1) BF3
- (2) SiF4
- (3) PF5

**Correct Option**: 1, 2, and 3.